(a) Technical Field
The present disclosure relates to an engine clutch transfer torque determining apparatus of a vehicle. More particularly, the present disclosure relates to an apparatus and method for determining an engine clutch transfer torque of a vehicle, such as an environmentally-friendly vehicle, that can determine a transfer torque of an engine clutch while running.
(b) Description of the Related Art
Nowadays, environmental pollution of the earth is a serious problem, and thus, use of nonpolluting energy is important. Particularly, vehicle exhaust gas is one of the major causes of air pollution.
In order to solve the problem of exhaust gas and to reduce fuel consumption, environmentally-friendly vehicle, such as a hybrid vehicle and an electric vehicle, have been developed. Many environmentally-friendly vehicles use a power generation device that is formed with an engine and a motor, and is driven by using power that is developed by a combustion action of the engine and power that is generated by a rotation of a motor using electrical energy that is stored in a battery.
In environmentally-friendly vehicles, a transmission of a Transmission Mounted Electric Device method (TMED) that connects a driving motor and a transmission is generally performed. In order to transfer power of the engine to a driving shaft, an engine clutch is mounted between the engine and the driving motor.
The environmentally-friendly vehicle also provides an Electric Vehicle (EV) mode that provides running of the vehicle with a torque of only a driving motor and a Hybrid Electric Vehicle (HEV) mode that provides running of the vehicle with the sum of an engine torque and a driving motor torque according to whether coupling of the engine clutch occurs. When the running of the environmentally-friendly vehicle is converted from the EV mode to the HEV mode, an engine speed and a motor speed are synchronized, in a power delivery process between the engine and the driving motor, by coupling the engine clutch and thus preventing a torque from being changed.
However, in an example case in which a battery maintains a low charge state, a temperature of the battery and the motor exceeds a predetermined reference temperature condition, and/or a road has a steeply slanted surface, the environmentally-friendly vehicle should be run by slip-controlling the engine clutch. In such a running condition, in order to slip-control the engine clutch, very accurate pressure control is required.
To this point, a transfer torque of the engine clutch is a torque that is transferred when a friction surface of both ends of the engine clutch physically contact one another, and may be basically predicted through an effective pressure and a friction coefficient. However, in a conventional method of determining a transfer torque, because a transfer torque can be determined only in P gear and N gear, the transfer torque cannot be determined while running the vehicle. Thus, there is not enough opportunity for determining the transfer torque, and accuracy of an engine clutch transfer torque may be deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore it may contain information that does not form the related art that is already known in this country to a person of ordinary skill in the art.